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What's the difference between a proc and a lambda in Ruby?
...using return in a proc returns from the enclosing block.
lambda { return :foo }.call # => :foo
return # => LocalJumpError: unexpected return
Proc.new { return :foo }.call # => LocalJumpError: unexpected return
So for most quick uses they're the same, but if you want automatic strict argu...
What is the 'pythonic' equivalent to the 'fold' function from functional programming?
...swered Apr 28 '12 at 18:35
Fred FooFred Foo
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...
What really happens in a try { return x; } finally { x = null; } statement?
...nt Test() {
try {
return SomeNumber();
} finally {
Foo();
}
}
compiles to:
.method private hidebysig static int32 Test() cil managed
{
.maxstack 1
.locals init (
[0] int32 CS$1$0000)
L_0000: call int32 Program::SomeNumber()
L_0005: stloc.0
...
Best way to give a variable a default value (simulate Perl ||, ||= )
I love doing this sort of thing in Perl: $foo = $bar || $baz to assign $baz to $foo if $bar is empty or undefined. You also have $foo ||= $bletch which will only assign $bletch to $foo if $foo is not defined or empty.
...
Why can a function modify some arguments as perceived by the caller, but not others?
...s make sense if you want to provide optional output destination as in: def foo(x, l=None): l=l or []; l.append(x**2); return l[-1].
– Janusz Lenar
Aug 31 '12 at 13:03
...
How to convert a std::string to const char* or char*?
...st character pointer.
1. Use the contiguous storage of C++11
std::string foo{"text"};
auto p = &*foo.begin();
Pro
Simple and short
Fast (only method with no copy involved)
Cons
Final '\0' is not to be altered / not necessarily part of the non-const memory.
2. Use std::vector<CharT...
Create list of single item repeated N times
... change one of them, they all change because they're all the same object:
foo = [[]] * 4
foo[0].append('x')
foo now returns:
[['x'], ['x'], ['x'], ['x']]
But with immutable objects, you can make it work because you change the reference, not the object:
>>> l = [0] * 4
>>> l[...
Get type of all variables
...f(1L) #a single numeric with L postfixed: integer
typeof("foobar") #A single string in double quotes: character
typeof(1) #a single numeric: double
typeof(list(5,6,7)) #a list of numeric: list
typeof(2i) ...
How to get process ID of background process?
... need to save the PID of the background process at the time you start it:
foo &
FOO_PID=$!
# do other stuff
kill $FOO_PID
You cannot use job control, since that is an interactive feature and tied to a controlling terminal. A script will not necessarily have a terminal attached at all so job c...
How to initialize a two-dimensional array in Python?
... for j in range (0, 10): } with a list /
new.append(foo) / comprehension /
twod_list.append(new) /
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